Conventional milling methods, particularly when used on whole grains, do not mill the husks, which are fibrous, to the same fine consistency as the white or inner kernel. Consequently, relatively large brown specks are always present in whole wheat flours. This affects not only the appearance of the flour but also the leavening of the flour due to the difference in size of the particles and the fact that the bran tends to absorb moisture unevenly.
In my earlier Canadian patent No. 1,222,234, I describe the milling of whole wheat flour by means of a rotary mill. Using this technique, the husk and the kernel are milled to the same particle size. This is accomplished through the use of a relatively fine screen surrounding rotary mill rotor which retains the bran component in the mill until it is the desired small particle size and can pass through the screen.
It has been found that the relatively fine screen used suffers considerable wear because of the action of the rotary mill and must be replaced frequently. Especially heavy wear has been found at the inlet of the screen.
The present invention is intended to ameliorate this rapid wear of the screen.